JP-2002-171688A discloses A/D conversion of currents fed to coils of a charging generator. Further U.S. Pat. No. 5,521,486 (JP-7-184330A) and JP-6-70599A disclose A/D conversion of currents and other parameters in an electric power generator to monitor an abnormality by a CPU.
However, an attempt to monitor many detection parameters by using a CPU as in the above technologies to detect an abnormality in equipment inevitably results in increasing the scale of A/D converter circuits and I/O circuits. Accordingly, the sizes of elements such as a microcomputer including a CPU increase, leading to an increase in cost. In the case of detecting an abnormality in equipment used in relatively hot environments such as an electric power generator mounted in a vehicle, malfunction may occur due to a leak current of circuit elements. Furthermore, circuits mounted in a vehicle are required to have very high reliability, and an increase in the circuit size would adversely affect the reliability.